Weird A4000T startup problems

[560SL]

Well, the weird thing is that it needs "warming up" before the system starts up properly. It used to be just a small annoyance but is going in the direction that it needs several minutes of power on before it can do a successful system startup.

Symptoms are freezings at hardware self- test, or shortly after. When the "warming up" is done, the system runs flawless.

I vaguely remember this topic has been discussed here before. Not sure if the conclusion then was oxidation on cpu port connector metal or some worn out capacitor.

Or maybe its running Java and need to optimize machine- code before starting workbench? :-P

Anyway, has anyone experienced this, and maybe know how to fix it?

[Dr.Bongo]

I would think it's a capacitor issue. Time to get them replaced

http://amigakit.leamancomputing.com/catalog/product_info.php?products_id=932

(I am in NO way affiliated with AmigaKit)

[560SL]

Yeah, I reckon that makes sense. Thanks for the tip, didn't know AmigaKit had this service.

Typical "wearing out" problem... though its funny, never happened to any other Amiga- model I have. Wonder if the "newer" models (A4000, A1200) are more prone to this kind of problem...

[Dr.Bongo]

Yeah, seems the newer 'surface mounted' (600,1200,A4k) Amiga's wear out much faster.
From experience, having the caps changed greatly helps. Audio on an older A4k is improved straight away.

[smerf]

Hi,

@560SL,

Have an Amiga 4000 desktop that does the same thing, I fount out that putting a new battery in then turning it on at least once a week to keep the battery charged stops this kind of behavior.

Check your battery, replace if the need be.
Turn it on at least once a week for a couple of hours.

When I did this it behaves like an Amiga, nice and smooth,

smerf

[nishtek]

Could be anything.  A4000T :
- get a AT power supply that you have tested
- get another cpu card and compare
- memory sticks should be tested on a PC machine and then used (a good reason to keep those old Pentium 2 mainboards with simms/edos)
- the scsi/audio connector properly seated
- roms properly seated.
- all other cards removed until you determine the issue.
if all else, then you can suspect ICs and / or capacitors.
thats our humble advice.

[KimmoK]

With that kind of symptoms I would take A4k apart and assemble it back and see if anything changed. But for my self made tower, it would be rather nasty job to do ... should start to seek for a commercial tower case for my A4000d parts...

[560SL]

Thanks for the tips!

The battery in A4000T is a coin- battery, only model that didn't come with the acid-barrell- type, as far as I know anyway. So it's not supposed to be charged. However, I will replace it as its a cheap test to see if things improve.

Still, as this problem has been creeping up, slow but steady, I get the feeling that it is some component/s that has been wearing out over the years. Don't know exactly when my unit was manufactured - it has no factory markings whatsoever - but the age must be closing in on 15 years.

Not sure about the PSU how it could be damaged in such a way so that it would give these kind of symptoms. Ive had this machine jammed with hardware like CSPPC, Mediator, Voodoo, P-IV etc. How can I know if the PSU has been damaged?

[nishtek]

> Not sure about the PSU how it could be damaged in such a way so that it would give these kind of symptoms. Ive had this machine jammed with hardware like CSPPC, Mediator, Voodoo, P-IV etc. How can I know if the PSU has been damaged?

Simple: measure the voltages of P/S, while power supply disconnected from amiga 4000.  note P8/P9 where they go etc.    a drop off in voltages could be the cause.  Mediator board could be failing.  I'd say Amiga technologies A4000T is pretty solid build boards so I doubt that this would go bad.  take all cards out and then boot only the amiga 4000T to OS 3.1 or something.  or boot from floppy drive.
it can be anything or any cards in the case that actually failed whcih is why I suggest you take it all out and boot only with motherboard - as with any PC motherboard troubleshooting.  if there was a sh***d of dust then you might know the answer to it as well.

[TrevorDick]

Hmm!, I have a A4000T (Escom build) that has a similar problem, but mine is definately the scsi HHD drive.  Once I can get it warm (to spin up), it works fine.

TrevorD

[magnetic]

The battery in A4000T is a coin- battery, only model that didn't come with the acid-barrell- type, as far as I know anyway.

Actually the A4000 Desktop REV D "CR" version (Cost Reduction) had the coin type battery as well as a on board surface mount 2mb Chip Ram. Oh, and some had onboard 030 and all of them moved the roms.

[Vlabguy1]

Well, the weird thing is that it needs "warming up" before the system starts up properly. It used to be just a small annoyance but is going in the direction that it needs several minutes of power on before it can do a successful system startup.

Symptoms are freezings at hardware self- test, or shortly after. When the "warming up" is done, the system runs flawless.

I vaguely remember this topic has been discussed here before. Not sure if the conclusion then was oxidation on cpu port connector metal or some worn out capacitor.

Or maybe its running Java and need to optimize machine- code before starting workbench? :-P

Anyway, has anyone experienced this, and maybe know how to fix it?

Check the A/V module card as well as the disk module for leaky caps.  My tower had the same issues long time ago.  Upon further inspection I noticed leaky caps as well as a few suspect ones near the Zorro slots.  I posted pictures here a while ago. Check them out..

I ended up getting new boards from Softhut..

Rich
ny